Field of the Invention
The present invention relates to a locational information transmission system, a locational information transmission apparatus, and an information processing device.
Description of the Related Art
In recent years, Global Positioning System (GPS) receivers have been installed in information terminals such as car navigation systems, smartphones, and tablet terminals, so that it is possible to readily use locational information using the GPS.
Further, a technique called Indoor MEssaging System (IMES) that makes locational information available even in an area of an underground mall is used as an indoor positioning technique. In the IMES, an indoor transmitter is disposed to transmit locational information about the indoor transmitter as radio waves (see Patent Document 1, for example). Further, there is an autonomous ultrasonic indoor positioning system using a location beacon transmitter that transmits ultrasonic signals at predetermined intervals (see Patent Document 2, for example).
For example, in a system that transmits locational information using radio waves such as Bluetooth (registered trademark) or Bluetooth Low Energy (BLE), locational information is transmitted in a relatively wide area (within a radius of 2.5 to 50 m, for example). By contrast, in such a system that transmits locational information using radio waves, intervals to transmit locational information are often set long (10 second intervals, for example) in terms of power consumption or the like. Such a system may not send highly-accurate locational information (within several meters of error, for example) to a moving information terminal.
By contrast, highly-accurate locational information is reported in a relatively narrow area by transmitting the locational information using sound waves such as ultrasonic signals. Further, an existing loudspeaker (as used in a building for announcement) is used to output sound waves and set intervals to transmit locational information shorter (one second intervals or continuously, for example) than in a system that uses radio waves. However, in the system that uses sound waves to transmit locational information, if locational information transmission devices (existing loudspeakers, for example) that output sound waves are distant from each other, obtained locational information may not be continuous.